To understand the importance of optical networking, the capabilities of this technology have to be discussed in the context of the challenges faced by the telecommunications industry, and, in particular, service providers. Most U.S. networks were built using estimates that calculated bandwidth use by employing concentration ratios derived from classical engineering formulas for modeling network usage such as the Poisson process. Consequently, forecasts of the amount of bandwidth capacity needed for data networks were calculated on the presumption that a given individual would only use network bandwidth six minutes of each hour. These formulas did not factor in the amount of traffic generated by different devices accessing the Internet. With the advent of the Internet and the ever increasing number of devices (e.g., facsimile machines, multiple phone lines, modems, teleconferencing equipment, mobile devices including smart phones, tablets, laptops, wearable devices, and Internet of Things (IoT) devices, etc.) accessing the Internet, there has been an average increase in Internet traffic of 300 percent year over year. Had these factors been included, a far different estimate would have emerged.
As a result of this explosive growth of devices, an enormous amount of bandwidth capacity is required to provide the services required by these devices. In the 1990s, some long-distance carriers increased their capacity (bandwidth) to 1.2 Gbps over a single optical fiber pair, which was a considerable upgrade at the time. At a transmission speed of one Gbps, one thousand books can be transmitted per second. However today, if one million families in a city decided to view a video on a Web site (e.g., YouTube, Home Box Office (HBO) on the go, DirectTV, etc.) then network transmission rates on the order of terabits are required. With a transmission rate of one terabit, it is possible to transmit 200 million simultaneous full duplex phone calls or transmit the text from 300 years-worth of daily newspapers per second.
When largescale data networks providing residential, commercial, and enterprise customers with Internet access were first deployed, the unprecedented growth in the number of devices accessing the network could not have been imagined. As a result, the network growth requirements needed in order to meet the demand of the devices were not considered at that time either. For example, from 1994 to 1998, it is estimated that the demand on the U.S. interexchange carriers' (IXC's) network would increase sevenfold, and for the U.S. local exchange carriers' (LEC's) network, the demand would increase fourfold. For instance, some cable companies indicated that their network growth was 32 times the previous year, while other cable companies have indicated that the size of their networks have doubled every six months in a four-year period.
In addition to this explosion in consumer demand for bandwidth, many service provider are coping with optical fiber exhaust in their network. For example, in 1995 alone many (ISP) companies indicated that the amount of embedded optical fibers already in use at the time was between 70 percent and 80 percent (i.e., 70 to 80 percent of the capacity of their networks were used the majority of the time to provide service to customers). Today, many cable companies are nearing one hundred percent capacity utilization across significant portions of their networks. Another problem for cable companies is the challenge of deploying and integrating diverse technologies in on physical infrastructure. Customer demands and competitive pressures mandate that carriers offer diverse services economically and deploy them over the embedded network. One potential technology that meets these requirements is based on multiplexing a large and diverse number of data, regardless of the type of data, onto a beam of light that may be attenuated to propagate at different wavelengths. The different types of data may comprise facsimile sources, landline voice sources, voice over Internet Protocol (VOIP) sources, video sources, web browser sources, mobile device sources including voice application sources, short messaging service (SMS) application sources, multimedia messaging service (MMS) application sources, mobile phone third party application (app) sources, and/or wearable device sources. When a large and diverse number of data sources, such as the ones mentioned in the previous sentence, are multiplexed together over light beams transmitted on an optical fiber, it may be referred to as a dense wave division multiplexing (DWDM).
The use of an optical communications module link extender (OCML) circuit as described herein allows cable companies to offer these services regardless of the open systems interconnection (OSI) model network layer (layer 3) protocols or media access control (MAC) (layer 2) protocols that are used by the different sources to transmit data. For example, e-mail, video, and/or multimedia data such as web based content data, may generate IP (layer 3) data packets that are transmitted in asynchronous transfer mode (ATM) (layer 2) frames. Voice (telephony) data may be transmitted over synchronous optical networking (SONET)/synchronous digital hierarchy (SDH). Therefore regardless of which layer is generating data (e.g., IP, ATM, and/or SONET/SDH) a DWDM passive circuit provides unique bandwidth management by treating all data the same. This unifying capability allows cable companies with the flexibility to meet customer demands over a self-contained network.
A platform that is able to unify and interface with these technologies and position the cable company with the ability to integrate current and next-generation technologies is critical for a cable company's success.
Cable companies faced with the multifaceted challenge of increased service needs, optical fiber exhaust, and layered bandwidth management, need options to provide economical and scalable technologies. One way to alleviate optical fiber exhaust is to lay more optical fiber, and, for those networks where the costs of laying new optical fiber is minimal, the best solution may be to lay more optical fiber. This solution may work in more rural, where there may be no considerable population growth. However, in urban or suburban areas laying new optical fiber may be costly. Even if it was not costly, the mere fact that more cable is being laid does not necessarily enable a cable company to provide new services or utilize the bandwidth management capabilities of the unifying optical transmission mechanism such as DWDM.
Another solution may be to increase the bit rate using time division multiplexing (TDM). TDM increases the capacity of an optical fiber by slicing time into smaller time intervals so that more bits of data can be transmitted per second. Traditionally, this solution has been the method of choice, and cable companies have continuously upgraded their networks using different types of digital signaling technologies to multiplex data over SONET/SDH networks. For example, Digital Signal (DS) DS-1, DS-2, DS-3, DS-4, and DS-5, commonly referred to as T1, T2, T3, T4, or T5 lines, are different carrier signals, that are transmitted over SONET/SDH networks that can carry any of the sources of data mentioned above, whose data rates increase with the number assigned to the DS. That is DS-1 was the earliest carrier signal used to transmit data over SONET/SDH networks, and has the lowest data rate and DS-5 is the most recent carrier signal use to transmit data over SONET/SDH networks with the highest data rate. Cable company networks, especially SONET/SDH networks have evolved over time to increase the number of bits of data that can be transmitted per second by using carrier signals with higher data rates. However, when cable companies use this approach, they must purchase capacity based on what the SONET/SDH standard dictates will be the next increase in capacity. For example, cable companies can purchase a capacity of 10 Gbps for TDM, but should the capacity not be enough the cable companies will have to purchase a capacity of 40 Gbps for TDM, because there are no intermediate amounts of capacity for purchase. In such a situation, a cable company may purchase a significant amount of capacity that they may not use, and that could potentially cost them more than they are willing to pay to meet the needs of their customers. Furthermore, with TDM based SONET/SDH networks, the time intervals can only be reduced to a certain size beyond which it is no longer possible to increase the capacity of a SONET/SDH network. For instance, increasing the capacity of SONET/SDH networks to 40 Gbps using TDM technology may prove to be extremely difficult to achieve in the future.